In experiments with mice, a team of scientists from the United States, Sweden and Japan has discovered that having a double dose of one protein is sufficient to change the normal balance of cells within the lining of the colon, thereby doubling the risk that a cancer-causing genetic mutation will trigger a tumor there. Roughly 10 percent of people have this double protein dose as well.
In the Feb. 24 online version of Science, the researchers report that mice engineered to have a double dose of insulin-like growth factor 2 (IGF2) develop more so-called precursor cells within the lining of the colon than normal mice. When these mice also carried a colon-cancer-causing genetic mutation, they developed twice as many tumors as those with normal IGF2 levels, the researchers report.

